Myofibroblasts Derived from Hepatic Progenitor Cells Create the Tumor Microenvironment  Sayaka Sekiya, Shizuka Miura, Kanae Matsuda-Ito, Atsushi Suzuki  Stem Cell Reports  Volume 7, Issue 6, Pages 1130-1139 (December 2016) DOI: 10.1016/j.stemcr.2016.11.002 Copyright © 2016 The Authors Terms and Conditions

Figure 1 HPCs Isolated from the Chronically Injured Adult Mouse Liver Have Trilineage Differentiation Potential (A) Experimental procedure to isolate and characterize HPCs. Wild-type mice were administered DDC for induction of CK19+ biliary lineage cells that contain a fraction of HPCs in the chronically injured liver. The liver tissues were then dissociated into single cells, and the CD133+CD45−TER119− biliary lineage cells were isolated by flow cytometry and clonally cultured in 96-well plates. HPCs that formed LCs and expanded in clonal culture exhibited the features of epithelial cells and produced hepatocytes and cholangiocytes as descendants, while maintaining undifferentiated cells by undergoing self-renewing cell divisions. Upon transplantation, HPCs marked by expression of GFP were also capable of reconstituting the hepatic lobule as FAH+ hepatocytes and forming the biliary ductal structures by differentiating into CK19+ cholangiocytes. We chose three independent HPC clones for examination. (B) In clonal cultures of HPCs, a small number of cells with the morphology of mesenchymal cells were present (arrowheads). (C) Immunofluorescence staining of α-SMA was conducted for cells in a clonal culture of HPCs. (D) The percentages of cells immunoreactive for α-SMA among HPC clones (HPC-C1, HPC-C2, and HPC-C3) were calculated after counting ∼1 × 105 cells in individual culture dishes. (E) Co-immunofluorescence staining of ALB with α-SMA and CK19 was conducted for cells in a clonal culture of HPCs. (F) Co-immunofluorescence staining of α-SMA with EdU was conducted for cells in a clonal culture of HPCs (arrowheads: α-SMA+ EdU+ cells), and the percentages of cells immunoreactive for EdU in α-SMA− or α-SMA+ cells were calculated after counting ∼800 or ∼20 cells, respectively, in individual culture dishes. The data represent means ± SD of three technical replicates (n = 3). DNA was stained with DAPI. Scale bars, 50 μm. See also Figures S1 and S2. Stem Cell Reports 2016 7, 1130-1139DOI: (10.1016/j.stemcr.2016.11.002) Copyright © 2016 The Authors Terms and Conditions

Figure 2 HPCs Have a Potential to Persistently Produce Myofibroblasts in Clonal Subcultures (A) Experimental procedure to perform subcloning experiments for three different HPC clones (HPC-C1, HPC-C2, and HPC-C3). Cells in cultures of each HPC clone underwent clone sorting by flow cytometry and were clonally cultured in 96-well plates. After LC formation and clonal expansion, three representative subclones of the individual primary HPC clones were chosen for examination. (B and C) The numbers of LCs in the wells of 96-well plates (B) and the numbers of LCs containing α-SMA+ cells in LCs (C) were counted. The percentages are shown. (D) Immunofluorescence staining of α-SMA and co-immunofluorescence staining of ALB with α-SMA and CK19 were conducted for cells in LCs formed from cells in cultures of a primary HPC clone. DNA was stained with DAPI. Scale bars, 0.5 mm (left panel) and 50 μm (right panels). (E) The percentages of cells immunoreactive for α-SMA among subclones of the three primary HPC clones were calculated after counting ∼1 × 105 cells in individual culture dishes. The data represent means ± SD of three technical replicates (n = 3). Stem Cell Reports 2016 7, 1130-1139DOI: (10.1016/j.stemcr.2016.11.002) Copyright © 2016 The Authors Terms and Conditions

Figure 3 Hepatoblasts Have a Potential to Differentiate into Myofibroblasts (A) Immunofluorescence staining of α-SMA was conducted for cells in cultures of hepatoblast clones (Hepatoblast-C1, Hepatoblast-C2, and Hepatoblast-C3), following isolation from the developing mouse liver. DNA was stained with DAPI. Scale bars, 50 μm. (B) The percentages of cells immunoreactive for α-SMA among the hepatoblast clones were calculated after counting ∼3 × 106 cells in individual culture dishes. The data represent means ± SD of three technical replicates (n = 3). Stem Cell Reports 2016 7, 1130-1139DOI: (10.1016/j.stemcr.2016.11.002) Copyright © 2016 The Authors Terms and Conditions

Figure 4 p53−/− HPCs Give Rise to a Small Number of Myofibroblasts in Culture (A) Experimental procedure to prepare p53−/− HPCs for in vitro analysis and transplantation. The CD133+CD45−TER119− cells isolated from the livers of DDC-treated p53−/− mice were clonally cultured in 96-well plates. HPCs that formed LCs and expanded in clonal culture were analyzed in culture and used for transplantation into NOD/SCID mice following transfection of a GFP-expressing vector. (B) Representative morphology of cells in a clonal culture of p53−/− HPCs (left panel). Co-immunofluorescence staining of ALB with α-SMA and CK19 was conducted for cells in a clonal culture of p53−/− HPCs (right panel). DNA was stained with DAPI. Scale bars, 50 μm. (C) The percentages of cells immunoreactive for α-SMA among p53−/− HPC clones (p53−/− HPC-C1, p53−/− HPC-C2, and p53−/− HPC-C3) were calculated after counting ∼1 × 105 cells in individual culture dishes. The data represent means ± SD of three technical replicates (n = 3). Stem Cell Reports 2016 7, 1130-1139DOI: (10.1016/j.stemcr.2016.11.002) Copyright © 2016 The Authors Terms and Conditions

Figure 5 Myofibroblasts Derived from p53−/− HPCs Create the Tumor Microenvironment (A) Three distinct p53−/− HPC clones gave rise to tumors at 2 months after subcutaneous injection into NOD/SCID mice. Arrows indicate tumors formed from each p53−/− HPC clone. (B) Serial sections of a tumor arising from a GFP-expressing p53−/− HPC clone were analyzed by H&E staining and immunohistochemical staining of GFP, α-SMA, and CK19. (C–F) Co-immunofluorescence staining of GFP with α-SMA (C and E) or CK19 (D) and that of GFP with E-cadherin and α-SMA (F) was conducted for p53−/− HPC-derived tumors formed in NOD/SCID recipient mice. Serial sections were used for the staining shown in (D) and (E). DNA was stained with DAPI. Scale bars represent 200 μm (B), 50 μm (C–E), and 10 μm (F). See also Figures S3 and S4. Stem Cell Reports 2016 7, 1130-1139DOI: (10.1016/j.stemcr.2016.11.002) Copyright © 2016 The Authors Terms and Conditions